/ 


H^rrocLB 


II 


Oavirtc^  bAnks  on  +b e. 
Mte%is%ippi  river 


The  person  charging  this  material  is  re- 
sponsible for  its  return  to  the  library  from 
I which  it  was  withdrawn  on  or  before  the 
Latest  Date  stamped  below. 

Theft,  mutilation,  and  underlining  of  books 
are  reasons  for  disciplinary  action  and  may 
result  in  dismissal  from  the  University. 

UNIVERSITY  OF  ILLINOIS  LIBRARY  AT  URBANA-CHAMPAIGN 

JUL  5 1975 

_ . 

JUN  1 * 1375 


L161  — 0-1096 


O -A.V OTG  BANKS 

On  the  Mississippi  River. 

% 


The  Mississippi  River  is  a succession  of  reverse  curves.  Except  at  or 
about  the  reversion  points,  there  is  generally  a steep,  caving  and  receding 
bank  on  the  concave  side,  and  a flat,  shoaling  and  advancing  bank  on  the 
convex  side.  The  material  from  the  concave  bank,  dropped  into  the 
swiftest  current,  is  rapidly  swept  away.  The  convex  side,  is  shoaler  and 
less  deeply  submerged,  by  water  more  lightly  charged  with  sediment 
While  the  extension  of  the  point  out  into  the  channel  may  be  as  rapid  as 
the  recession  of  the  opposite,  or  concave  shore,  its  elevation  to  high 
water  level  is  very  gradual.  As  might  be  expected  from  this  action,  a 
comparison  of  surveys  shows  a gradual  but  persistent  widening  of  the 
high  water  river.  As  the  width  increases,  its  mean  depth  diminishes,  A 
characteristic  shape  of  bed,  resulting  from  this,  has  deeper  water  along 
either  bank,  and  a middle  ground,  or  bar  area,  at  the  intermediate  node 
or  reversion  point  between  bends.  This  is  the  origin  of  many  islands. 
The  absence  of  defined  channels  across  this  bar  area,  from  one  pool  to 
another,  is  the  obstruction  to  low  water  navigation.  The  development  of 
channels  through  it  is  the  result  of  the  increase  of  local  velocity,  by  the 
reduction  of  sectional  area  as  the  water  falls.  If  these  channels  are  nu- 
merous, as  frequently  occurs,  they  are  tortuous,  uncertain,  and  of  less 
depth. 

“ These  bars  are  not  permanent  in  position ; on  the  contrary,  they  are 
prone  to  shift  as  the  bends  become  more  acute,  extend,  or  move  down- 
ward. Indeed,  under  the  general  rule  that  the  bars  form  at  the  reversion 
point  of  curves,  it  is  evident  that  their  position  must  vary  as  these  curves 
vary,  and  that  the  holding  of  the  curves,  by  revetment  or  otherwise,  is 
an  essentially  early  step  in  the  control  of  the  river.  It  antedates  logi- 
cally the  retrenchment  which  is  to  deepen  the  water  at  the  bars.”  * 

From  caving  banks  is  derived  a large  part  of  the  material  of  which 
bars  are  composed.  The  banks  are  generally  of  sand  and  clay,  seldom 
purely  of  either  material,  but  mixed  in  different  proportions  according  to 
the  conditions  under  which  they  were  built.  The  finer  and  lighter  parts 
float  long  distances  with  low  velocity,  and  are  deposited  in  quiet  water* 
under  the  shelter  of  willow  points.  The  sediment  from  the  Mississippi  is 
so  light  that  at  times,  1200  miles  below  its  mouth,  at  medium  and  low 
stages,  and  correspondingly  small  velocities,  not  only  the  charge  of  sedi- 
ment per  unit  of  measure,  but  even  the  total  quantity  afloat,  is  greater 
than  at  times  of  flood  from  the  Ohio,  when  the  discharge  and  velocity  are 
largely  increased. 

f *Prof.  H.  Mitchell— App.  M.  R.  C.  Rep.  1882,  p.  263. 


LIBF.  :Y 

Of  • |£ 

UNIVERSITY  OF  ILLINOIS 


V 


2 


The  more  important  part,  however,  the  sand,  and  fine  gravel,  sinks 
rapidly,  forming  a loose  and  shifting  bed,  which  is  shaped  into  sand-waves 
and  bars  by  the  forces  of  the  river,  constantly  changing  in  direction  and 
intensity.  If  it  falls  in  a pool,  where  the  scouring  power  of  the  higher 
stages  is  concentrated,  the  next  flood  sweeps  it  down  to  the  bars  in  the 
wider  sections  below,  where  the  current  spreads,  and  its  transporting 
power  abates.  • From  this  halting  place,  where  the  current  becomes  rela- 
tively greater,  as  lower  stages  prevail,  it  is  scoured  down  to  the  compara- 
tively still  pool  below.  The  range  of  elevation  of  these  bars,  during  the 
annual  oscillations  of  the  river,  frequently  exceeds  the  depths  found  on 
them  at  low  water.  A high  water  survey,  reduced  to  low  water  gauge 
readings  would  exhibit  numerous  dry  bars  extending  across  the  bed. 
The  more  important  down  stream  movement  of  sediment,  is,  therefore, 
intermittent,  and  it  can  be  understood  that  the  same  material  may  enter 
successively  into  the  composition  of  each  bar  as  it  moves,  by  semi-annual 
excursions,  towards  the  sea. 

The  extreme  variations  of  width  now  existing  in  the  river,  with  a 
tendency  towards  further  increase,  are  not  normal,  but  exaggerated  by 
caving.  The  physical  history  of  the  river  is  not  one  of  growth  from  a 
narrow  to  a wide  stream,  but  of  the  retrenchment  of  a wider  expanse  of 
surface  to  a confined  and  limited  waterway,  of  an  estuary  to  a river.  The 
bed  still  strives  to  conform  its  dimensions  to  the  smallest  section  that  will 
contain  the  volume  of  discharge,  and  to  a shape  that  will  offer  least  re- 
sistance. The  opposite  tendency  which  is  now  observed  marks,  by  dis- 
turbed regimen,  the  presence  and  control  of  abnormal  influences.  It  is 
therefore  just  to  expect  that,  if  the  elongation  of  points,  and  the  growth 
of  middle  bars  were  resisted  by  permanent  banks,  the  material  now 
causing  their  extension  towards  the  retreating  shore,  would  be  deposited 
over  areas  outside  of  the  required  bed  limits,  so  as  to  raise  them  to  bank 
level,  and  thus,  by  narrowing  the  width  restore  conditions  more  favorable 
both  for  navigation  and  discharge.  The  obvious  illustrations  of  this  are 
the  exceedingly  narrow  and  deep  sections  along  the  bluffs  at  Columbus, 
Fulton,  Randolph,  Memphis,  the  old  Vicksburg  and  Grand  Gulf  channels, 
and  the  other  bluffs  below. 

While  this  description  is  generally  true  of  the  character  of  the  changes 
taking  place  throughout  the  River,  it  should  be  understood  that  the  partr  | 
where  the  results  have  been  disastrous,  or  the  danger  is  imminent,  are,  in 
the  main,  localized  and  cou fined  to  certain  reaches  where  navigation  is 
impaired,  or  large  interests  are  menaced.  While  in  a sense  it  is  true  as  to 
all  parts  of  the  river,  it  is  not,  in  such  sense  as  to  require  the  revetment 
of  all  of  them. 

There  is  fair  agreement  among  engineers  as  to  the  causes  now  im- 
pairing the  navigation  and  discharge  capacity  of  the  river.  The  im- 
portance of  contracting  the  lake-like  expansions  at  parts  of  its  course, 
and  of  such  works  as  will  promote  uniformity  of  section  and  velocity  n 
generally  acknowledged.  There  are,  however,  different  opinions  as  tc 
the  means  of  reaching  this  result.  There  is  a contention  whether  tin 
direct  application  of  protective  work  to  a caving  bank  is  necessary  t< 
hold  it,  or  whether  its  caving  can  be  indirectly,  or  incidentally  checked  >.i 


3 


the  uniformity  of  section,  velocity  and  sediment  in  suspension  which,  it 
is  claimed,  will  result  from  such  works  of  contraction  as  will  give  ease 
and  safety  to  navigiition,  and  prevent  destructive  floods.  On  the  one 
hand  it  is  maintained  that  the  adjustment  between  the  velocity  and  the 
charge  of  sediment  carried  by  each  unit  of  discharge  is  so  close,  that 
were  the  section  and  velocity  uniform,  the  water  would  always  have  a 
load  of  sediment  proportioned  to  that  velocity,  and  would  pass  through 
its  channel  without  loss  or  gain  of  solid  matter — or,  without  erosion  of 
its  banks.  It  will  be  observed  that  this  hypothesis  excludes  the  effect  of 
impact  in  destroying  the  banks.  It  is  held,  on  the  other  hand,  that, 
while  velocity  and  the  degree  of  saturation  with  sediment  are  related 
yet  it  is  and  always  will  be  necessary  to  protect  the  banks,  to  a greater 
or  less  extent,  in  order  to  hold  the  contraction  obtained  by  dikes  pro- 
jecting in  the  channel,  to  prevent  the  destruction  of  this  dike  work  by 
changes  in  the  River  above,  and  to  check  the  deterioration  of  reaches 
which  are  now  in  satisfactory  condition. 

I shall  give  the  first  of  these  views  as  presented  by  its  most  distin- 
guished advocate,  Capt.  Jas.  B.  Eads: 

“ The  Mississippi  is  simply  a transporter  of  solid  matter  to  the  sea. 
“ This  consists  chiefly  of  sand  and  alluvion,  which  is  held  in  suspense  by 
“the  mechanical  effect  of  the  current.  A small  portion,  consisting  of 
^ “larger  aggregations,  such  as  gravel,  boulders,  small  lumps  of  clay,  and 
• *'  drift-wood,  is  rolled  forward  along  the  bottom.  By  far  the  greater 
“ portion  is,  however,  transported  in  suspension.  The  amount  of  this 
, “ matter,  and  the  size  and  weight  of  the  particles  which  the  stream  is 
“ enable  to  hold  up  and  carry  forward,  depend  wholly  upon  the  rapidity 
“ of  the  stream,  modified,  however,  by  its  depth.  The  banks  and  bottom 
being  chiefly  sand  and  alluvion,  are  easily  disintegrated  by  the  rnove- 
ment  of  the  waters,  hence  the  amount  of  load  lost  by  any  slackening  of 
“ the  current  at  one  place,  will  be  quickly  recovered  in  the  first  place 
“ below  where  the  current  is  again  increased. 

“ The  popular  theory  advanced  in  many  standard  works  on  hydraulics, 
“ to-wit : that  the  erosion  of  the  banks  and  bottom  of  streams  like  the 
Mississippi  is  due  to  the  friction  or  impingement  of  the  current  against 
them,  has  served  to  embarrass  the  solution  of  the  very  simple  phenom- 
•“  ena  presented  in  the  formation  of  the  delta  of  the  Mississippi,  because 
it  does  not  explain  why  it  is,  that  under  certain  conditions  of  the  water 
it  may  develop  with  a gentle  current  an  abrading  power,  which,  under 
other  conditions,  a great  velocity  fcannot  exert  at  all.  A certain  velocity 
gives  to  the  stream  the  ability  of  holding  in  suspense  s proportionate 
quantity  of  solid  matter,  and  when  it  is  thus  charged  it  can  sustain  no 
more,  and  hence  will  carry  off  no  more,  and  therefore  cannot  then  wear 
“ away  its  bottom  or  banks,  no  matter  how  directly  the  current  may 
, “ impinge  against  them. 

“ In  the  upper  portions  of  the  delta  (which,  according  to  some  writers 
“ extends  a few  miles  above  Cairo),  the  width  of  the  river  is  very  irregu- 
“ lar.  When  a rise  occurs,  the  current  is  increased  in  the  narrow  parts  of 
r the  river,  and  the  carrying  capacity  of  the  stream  consequently  becomes 
-“greater  and  it  at  once  takes  up  an  additional  load.  WThen,  however,  as 


Li  BP  ; aY 

Of  • ;i’E 

UNIVERSITY  OF  ILLINOIS 


4 


“ the  stream  flows  on,  it  enters  a wide  expanse,  the  current  is  slackened 
“ and  the  excess  of  load  is  dropped  to  the  bottom,  and  thus  shoals  or  bars 
“ are  formed.  From  such  expansion  of  channel  way,  the  volume  of  water, 
“ thus  relieved  of  a portion  of  its  load,  passes  into  another  one  of  the 
“ narrow  parts  of  the  channel,  and  here  its  current  by  contraction  is 
“ again  accelerated,  and  the  increased  load  which  it  can  carry  is  immedi- 
“ ately  scoured  up  from  the  bottom  and  sides  of  the  channel.  In  the 
“ bends,  the  centrifugal  force  of  the  water  makes  the  current  more  rapid 
“ on  the  cancave  bank  of  the  stream,  and  there  it  usually  gets  its  addi- 
“ tional  load,  and  the  caving  in  of  the  bend  testifies  to  the  rapacity  of  the 
“ water  at  that  point  of  its  course.  Once  loaded,  however,  it  can  carry 
“ no  more,  and  hence-  it  may  sweep  around  half  a score  of  other  bends 
“below  with  equal  velocity,  without  injury  to  them.  If  it  encounter 
“ another  expanse,  however,  it  again  loses  part  of  its  velocity,  and  with 
“ it,  part  of'its  load,  to  be  recovered  again  in  the  narrow  parts  of  its  chan- 
“ nel  below.  It  is  evident,  therefore,  that  if  the  channel  were  at  all 
“ uniform  in  size,  the  current  would  be  more  constant,  and  the  alternate 
“ depositing  and  recovery  of  part  of  the  burden  of  the  stream  would  be 
“prevented.  This  loading  and  unloading  is  synonymous  with  caving 
“ banks  and  sand  bars. 

“ The  lower  part  of  the  river,  nearly  all  the  way  from  Red  River  to  the 
“mouths  of  the  passes,  is  remarkably  uniform  in  width,  and  is  therefore 
“ comparatively  free  from  falling  banks  and  shoals.  This  part  of  the  river 
“ is  transporting  its  load  with  great  regularity,  and  without  interruption, 
“ to  the  sea ; whilst  that  above,  owing  to  the  alternating  contractions 
“and  expansions  in  its  channel,  transports  its  burden  with  great  irregu- 
“ larity,  dropping  a part  here  and  taking  up  a part  there,  and  thus  by 
“ successive  stages,  from  season  to  season,  it  is  borne  forward.”  * 

“ If  the  quantity  of  suspended  sediment  is  regulated  by  the  current 
“ and  if  the  bed  of  the  river  is  formed  of  its  own  sedimentary  deposits 
“ instead  of  this  unyielding  and  marble-like  clay,  then  it  is  entirely  prac- 
ticable to  lower  its  flood-line  or  slope  and  deepen  its  channel  by  simply 
“ constructing  light  willow  or  brush  dams  during  low  water  on  the  shoals 
“ which  are  then  dry,  or  nearly  so,  at  the  various  wide  places  in  the  river 
“ where  the  bars  always  exist.  These  dams  would  cause  the  deposit  of 
“ more  sediment  on  the  shoals  by  checking  the  current,  and  would  deepen 
“ the  contracted  channels  that  would  remain  by  increasing  the  current  in 
“ them.  In  this  way  the  high  water  channel  would  be  brought  to  a com- 
“ parative  uniformity  of  width  by  gradually  encouraging,  from  year  to 
“ year,  the  deposition  of  sediment  over  the  wide  expanses,  and  this  uni- 
“ formity  of  depth,  would  practically  stop  the  caving  of  the  banks.”  t 
“ I declared  that  the  revetment  of  caving  banks  would  be  enormously 
“ expensive  and  wholly  unnecessary,  and  I desire  now  to  repeat  that  I 
“ never  have  sanctioned  the  revetment  of  the  banks,  because  of  its  enor- 
“ mous  expense,  and  because  I am  sure  it  is  wholly  unnecessary  before  the 
“ rectification  of  the  high  water  channel.  I believe  that  no  real  succes. 
“ can  ever  be  achieved  unless  the  principle  of  contracting  the  high  wTate,„ 

* Mississippi  Jetties,  29,  30,  31.  Cortliell,  pp.  29,  30,  31.  * 

t Letter  to  President  of  Miss.  Riv.  Com.  Jan.  20, 1886.  f 


1 


“ channel  be  constantly  adhered  to,  and  all  other  works  be  made  simply 
“ auxiliary  and  subsequent  thereto,  and  be  regarded  as  only  of  secondary 
11  importance.”  * 

These  extracts  present  clearly  and  eloquently  this  attractive  theory. 
It  would  be  greedily  accepted,  if  it  agreed  with  observations,  or  explained 
phenomena.  Unfortunately,  it  does  neither. 

Those  who  reject  this  hypothesis  contend  that  the  law  governing  the 
relation  of  velocity  to  sediment  in  suspension  is  modified  by  active  but 
obscure  conditions,  as  is  proved  by  all  observations  on  the  Mississippi 
River;  and,  that  its  practical  results  are  not  apparent  in  the  surveys  of 
the  River,  or  the  works  for  its  improvement. 

I submit,  in  tabulated  form,  the  results  of  every  set  of  velocity  and 
sediment  observations  ever,  to  my  knowledge,  made  between  Cairo  and 
the  head  of  the  Passes.  The  velocities,  except  in  one  table,  are  graded 
in  the  first  column,  and  the  discordant  sediment  results  placed  in  the  last. 
In  the  exceptional  case  (Carrollton,  lSSl-^)  this  order  is  reversed,  and 
the  amount  of  sediment  is  graded  in  the  first  column,  and  the  accom- 
panying velocities  transferred  to  the  last.  The  sixth  table  is  constructed 
from  the  other  five : 

Of  the  observations  furnishing  data  for  these  tables,  those  at  Carrollton 
in  1851 — 52  and  at  Columbus  in  1858  were  made  by  Humphreys  and  Abbot ; 
those  at  Columbus,  in  1879,  by  what  was  styled  the  Low  Water  Board  of 
that  year,  and  those  at  Fulton  and  Carrollton,  1879—80,  by  the  Mississip- 
pi River  Commission. 

These  tables  show  clearly  that,  while  the  same  velocity  may  be  main- 
tained for  some  time,  or  may  recur  many  times  during  the  observations, 
it  is  not  necessarily  accompanied  by  similar  and  proportionate  charges  of 
sediment.  The  relation  is  disturbed  and  largely  controlled'  by  causes 
other  than  velocity  and  depth,  among  which  the  tributary  contributing 
most  to  the  discharge,  and  the  character  of  the  bed,  may  be  assigned  im- 
portant parts. 

That  the  irregularities,  or  departures  from  a fixed  charge  of  sediment, 
per  unit  of  measure,  for  certain  velocities,  which  appear  throughout  the 
tables,  are  only  modifications  of  the  law  resulting  from  differences  in  the 
depth  of  the  river  is  not  apparent,  and,  to  say  the  least,  requires  further 
investigation  before  it  can  be  accepted  as  a scientific  and  satisfactory  ex- 
planation. 

* Letter  to  President  Miss.  Kiv.  Com.  Jan.  i886. 


6 

VELOCITY  AND  SEDIMENT  OBSERVATIONS 


I-  lii^OX.I.TO  JSr,  1851— 35S_ 


Weekly  Aver- 
age of  grams 
in  600  grams  of 
water. 

Velocity  in  feet  per  sec- 
ond during  week. 

Weekly  Aver- 
age of  grams 
in  600  grams  of 
water. 

Velocity  in  feet  per  sec- 
ond during  week. 

.094 

1.42-1  80 

.276 

5.55 

.094 

1.88 

.282 

1.82 

.097 

2.55 

.308 

3.26  to  4.66 

.121 

1.51 

.344 

6.06  to  6.22 

.350 

3.41—4.16 

.131 

3.77—3.89 

.369 

2.36—2.52 

.139 

1.75-1.79 

.414 

2.90—3.02 

.141 

3.66—4.01 

.442 

5.-6— 6.13 

.142 

1.64—1.66 

.443 

4.51—458 

.148 

1.58—1.60 

.459 

4.79 

.151 

1.70—1.75 

.469 

4.76—4.79 

.165 

1.64—1.83 

.474 

3.15—3.30 

.169 

3.87—4.50 

.475 

4.13-4.38 

.184 

2.14 

.510 

2.99 

.184 

2.03 

.513 

3.25 

.187 

4.69-  4.75 

.5*21 

3.36—3.42 

.192 

2.28  . 

.539 

4.23—4  34 

.197 

1.60—1  74 

.591 

3.87—4.37 

.199 

1.69 

.594 

5 60—5.82 

.204 

1.99 

.599 

4 70—4.78 

.205 

4 64—5  64 

.614 

5.04—5.57 

.212 

4.90— 5 10 

.627 

4.53-4.85 

.228 

1.93  . 

.643 

4.82 

.241 

5.94—5  99 

.692 

3 64—3.66 

.255 

5 90—607 

.918 

4 33  to  4.47 

.266 

1 94—2.18 

II. 

OA.1S  ROLLTON, 

1879— 780. 

Mean  velocity 
in  feet  per  sec- 
ond. 

Periods  of  ob 
servation. 

No.  of  observa- 
tions in  each 
period. 

Extreme  range 
of  observations. 

Average  mille- 
grams  of  sedi- 
m’nt  in  500  cubic 
centimetres  of 
water. 

1}  to  2 

1 

1 

145 

2 

2 

125  to  170 

142 

2 to2£ 

1 

3 

2 15  to  375 

312 

2 

2 

190 

2£  to  3 

1 

2 

390  to  500 

445 

2 

1 

265 

3 to  3i 

1 

1 

400 

2 

1 

330 

3 

1 

470 

CO 

o 

1 

. l 

270  to  285 

277 

2 

2 

335  to  380 

357 

3 

i 

575 

4 to  4* 

1 

i 

670 

2 

i 

230 

3 

2 

510  to  540 

525 

4j  to  5 

1 

1 

310 

2 

1 

210 

5 to  5| 

1 

1 

535 

2 

1 

215 

5i  to  6 

1 

2 

370  to  385 

377 

III. 


COLUMBUS,  1858- 


Mean  velocity 
in  ft.  per  sec’d. 

Periods  of 
Observation. 

No.  of  Obsrva’ni: 
in  each  period. 

Range  of  Obser- 
vations during 
Period. 

Average  No.  of 
Grams  Troy  per 
cubic  ft.  of  water 

H to  2 

1 

22 

44  to  221 

130 

2'  “ 2* 

1 

9 

163  to  472 

260 

2 

8 

125  to  258 

188 

3 

1 

354 

2*  to  3 

1 

4 

546  to  708 

638 

2 

l 

281 

3 to  3£ 

1 

5 

422  to  598 

535 

2 

1 

502 

Si  to  4 

1 

7 

465  to  664 

619 

2 

3 

280  to  391 

325 

3 

5 

383  to  628 

502 

4 

3 

317  to  374 

347 

4 to  4i 

1 

2 

605  to  641 

623 

2 

2 

406  to  738 

572 

3 

2 

140  to  266 

203 

4 

3 

354  to  478 

418 

4£  to  5 

1 

1 

269 

2 

1 

269 

3 

2 

524  to  531 

527 

4 

5 

332  to  797 

564 

5 to  5i 

1 

1 

316 

2 

1 

280 

3 

1 

635 

5i  to  6 

1 

2 

235  to  279 

257 

2 

1 

539 

6 to  6£ 

1 

1 

490 

6i  to  7 

1 

1 

269 

2 

1 

288 

3 

5 

147  to  294 

204 

4 

1 

199 

7 to  7\ 

1 

5 

211  to  307 

285 

2 

2 

470  to  538 

504 

3 

1 

278 

4 

5 

235  to  382 

307 

5 

1 

155 

7i  to  8 

1 

1 

258 

8 to  8i 

1 

1 

355 

2 

1 

223 

IV. 

COLUMBUS, 

1879. 

Mean  velocity  in 

Periods  of  ob 

No.  of  observa- 

-  Range  of  obser- 

Av.  No.  grams 

feet  per  second. 

servation. 

tions  in  each 

l vation  during 

per  cub.  foot  of 

period. 

each  period. 

water. 

2 to  2£ 

1 

3 

22  to  37 

29 

21  to  3 

1 

17 

20  to  65 

41 

2 

4 

27  to  29 

28 

3 to  31 

1 

25 

29  to  111 

56 

31  to  4 

1 

1 

5 

2 

1 

6 

3 

2 

146 

4 to  41 

1 

5 

5 to  7 

6 

2 

2 

22  to  27 

24 

41  to  5 

1 

2 

10  to  35 

42 

2 

5 

27  to  55 

37 

5 to  1 

1 

2 

11  to  12 

11 

2 

2 

42  to  48 

45 

n * 


FULTON,  l879-380. 


Mean  Velocity 
in  ft.  per  secn’d 

Periods  of 
Observations. 

No.  of  Ob’ns 
in  each  Period. 

Eange  of  Obser 
vations  during 
each  Period. 

Average  No.  of 
. Millegrams  of 
Sediment  in  500' 
Cubic  Centiin. 

2 to  2i 

1 

8 

250  to  390 

298 

2 

14 

300  to  470 

354 

2jt  to  3 

1 

12 

340  to  570 

452 

2 

5 

270  to  388 

318 

3 

5 

400  to  460 

428 

3 to  3* 

1 

4 

240  to  450 

317 

2 

5 

430  to  810 

605 

3 

8 

450  to  630 

517 

3-J  to  4 

1 

9 

230  to  325 

274 

2 

4 

670  to  845 

734 

4 to  4£ 

1 

2 

190  to  230 

210 

2 

8 

355  to  445 

407 

3 

1 

255  to  *95 

272 

4 

13 

440  to  620 

521 

5 

2 

765  to  790 

777 

44  to  5 

1 

2 

250  to  260 

255 

2 

2 

450 

3 

4 

400  to  450 

426 

4 

6 

580  to  950 

781 

5 

4 

565  to  920 

776 

5to  5i 

1 

1 

555 

2 

1 

388 

3 

2 

850  to  880 

865 

4 

2 

925  to  935 

930 

5i  to  6 

1 

1 

235 

2 

• 8 

350  to  690 

279 

3 

2 

340  to  380 

360 

4 

2 

830  to  960 

895 

5 

4 

755  to  870 

826 

6 to  6i 

1 

2 

335  to  370 

352 

2 

1 

195 

3 

6 

205  to  385 

312 

4 

1 

375 

5 

2 

270 

6 

5 

830  to  1160 

993 

6i  to  7 

1 

1 

920 

o 

1 

385 

3 

1 

170 

4 

4 

330  to  1010 

562 

7 to  7* 

1 

5 

255  to  545 

390 

2 

4 

315  to  705 

496 

3 

1 

135 

74  to  8 

l 

1 

145 

I . pi 

' 1 


9 


VI.  C.A  IRIROIlILTOIINr,  1851’-53- 


Date. 

Gauge. 

Discharge  cubic 
feet  per  second 

Velocity,  feet 
per  second. 

Prop,  of  sedi- 
ment by  wt. 

Total  lbs.  of 
sediment. 

January  21 

5. 

482,392 

3. 

1 

1177 

1 

654 

25,616 

3d  week  June 

11.6 

779,384 

4.40 

74,482 

April  1 

15.25 

1,112,559 

5.96 

1 

2490 

27,924 

COLUMBUS,  1858. 

August  30 

13. 

267,700 

2.55 

1 

619 

1 

549 

1 

27,027 

July  22 

23.7 

596,350 

4.64 

67,899 

June  28 

38. 

1,156.960 

7.23 

1 

2823 

25,618 

June  14 

39.8 

1,318,733 

8.04 

1 

1354 

60.850 

COLUMBUS,  1879. 

July  2 

23.4 

410,000 

3.75 

195 

131,835 

April  5 

33.65 

720.000 

5.20 

1 

2489 

18,078 

FULTON,  1879-’80  # 


July  31 
March  28 

168.25 

188. 

340,000 

1,070,000 

3.5 

7.75 

l 

610 

1 

3453 

34,83fc 

19,367 

CARROLLTON,  1879-’80. 

August  19 

2. 

315,000 

2.36 

1333 

14,769 

August  9 

4.40 

425,000 

2.93 

1 

1111 

23,909 

May  19 

13.40 

850,000 

5 34 

1 

2305 

23,047 

The  following  table  is  compiled  from  comparative  surveys,  by  the  Mis- 
sissippi River  Commission,  of  the  bank  line  of  the  river  from  Cairo  to*  Mem- 
phis. It  further  shows  that  the  amouut  of  caving  of  banks  is  not  depen- 
dent upon  the  degree  to  which  the  water  flowing  against  them  is  charged 
with  sediment.  The  demarkation  between  the  muddy  discharge  from 
the  Mississippi  and  the  clear  water  from  the  Ohio  is  frequently  observa- 
ble, by  the  eye,  for  twenty  or  thirty  miles  below  their  junction,  and,  by 
the  sediment  trap,  for  two  or  three  hundred.  Notwithstanding  this,  the 
caving  on  the  Right  bank,  washed  by  water  more  heavily  charged  with 
sediment,  exceeds  that  of  the  Left  bank,  along  which  flows,  with  equal 
velocity,  the  comparatively  clear  discharge  of  the  Ohio. 


-‘O'l— 'H*i— iHHCOtOtOtOtOCO 

~ ^ H M a /T  o m /i  'n  nri  i— 


pppppp  p oj  jx>  jcp  oohmomcoi 

^ •;  y x S S22S^®^mo®mVo 
2222=>®oooo©0'oooooo 
ooooooooooo o o o o o o o 


|9  ^ ® f ^ O tt’  OI  iO  o v' 

tCC^MJCh-mtCHMOOiMOiXODW 


‘OMO< 


v-^r  '•'V  VV  I W'  W'  r— • VW  W' 

OKCOl  Cobobobobo'^bobobobobobobobo 
cnmcioicnoioi^cnwyiyooooo 
poo  oooooooooooooo 


JO  COJX  O'  W Oi  p COJOp  XO  — H*  p JO  p JO' 
bn  H-i bn  Cl  H*  O ' CO  CO bu bo  <t 'to  00  <1  be bo  bn bo 
cooTOHOiocoiHaHvjojooioawH 
o-  jo  p p oj  o ac  to  jo  jx  p p o o p p p p 
o bo  bo  boob  © Vt  bo  bobooo  bo  o bo  bo 

©OOOOOOOOOOOOOO  O' OO 
oooooooooooooooooo I 


<t05Cn.U00C0tSoCCa0*^Cn>UC0t3i>Si-‘ 
pJO  CO  JO  lUp  p JO  pp  H-k  JO  JO  O 00  CO  JO 

~<tb— bobubo'oc'^t  <t'aobo  bn  bob-*  bo  O' Vibe 

bC'OQO^OtSC’b^O'OjbbCOCO'W 
05  to  JO  p JO  p p P O'  p pt  JO  p p p p p 
'bs  05  05  bo  bo  bo  bo  bobo  05  "os  br.  bo  os  bo  bo  "os 
ooooooooooooooooo 

OOOOOOOOOOO  O O'  O O O O' 


P3  CO 

® ® 
pj  ® 

B 

£5  HH 
p * 
Pi 


SLOgOgg'pOp.p-^  M-  ^ c B 


co  S 

2C  r- J 

5-  P 
® ?b 
3 ® o ® 
i-j  ^ 


P 00  <=♦  3 fc-  K - 


Pi  p 

C.3 


=^0*53  ® S 2 3 ® 
~ © ® cc  -o  cc  ®,  uj 


p * 


o O O O o O CO 

O O O o o o o 
o o o®  o o o 


|_L  O' 

O' JO, 
© to 
o o 
o o 


oocooooocnoo 

oooooooooo 

oooooooooo 


CO  CO  CO  CO  CO  to  to 
05  0*  to  O GO  O' 
p p J©  JO  JO  p j— 1 

bo  bo  bo  bo  bo  bo  bo 
O O O O O O o 
o o o o o o o 


to  to 

r-i  O 

OC  C0V 

©bo' 
o o 
o o 


ODOOODO'O'O'O'O'O 
ooooooooo 
o o ooo o o o o 


> 
CfQ 
I or? 

I ® 

or1; 

I I 


H*  tO  H- 1 H-i  I— 1 I—1 

bpbOppWMtOOpjtO  ppj©  p 

VtBboO'Vt-b  CO  03  to  © © to  bo  05  bX'  05  o 
©C'HOWbCOOa^c-bCnajtO^OO 
OQObC  p 35  WOHOOpbOO  OODO  © © 

bo  bo  bo  bo  © bo  bn  bo  V bo  co  bo  bo  bo  bo  bo  bo  o bo 

OOO  OOO  OOOOOOOOOOO  O'  o 

oooooooooooooo  ooooo 


O'  4- 
p CO 

CP  <1 
p p 

'bobs' 
o o 
-o  o 


>U  CO 
pp 
O' bn' 
H*  O 
35  to 
to  bo 
o o 
o o 


to  Hi 

H* 

O' bp 
o <35 
to  35 
to  bo 
o o 
o o 


OCMMCJ'^wtOHHHH 
p CO  O X p 1-ppp J©  Ojl 

bn  bo  bo  bo  05  bubo  bo  obs  u® 

tOOSGffi-lOQCUCSCD^IO 
O 05  p O' Jit  tOGOOCpDJCOO 

bo  <t  "■i  I bo  bo  bo  O bo  p bo  bo  bo 

OOOOOOOOOOOO 

oooooooooooo 


0 

ffi 

H 

td 

p 

%\ 


o 

o 

s 

"0 

> 

co 

> 

H 

h— ( 

<J 

n 

o 

> 

<b 

H— t 

z 

o 

o 

z 

co 

H— < 

o 

EC 

H 

> 

z 

V 

r 

PI 

H 

ro 

> 

z 

0) 


11 

Between  Cairo  and  Memphis  the  bluffs,  composed  of  less  erosible  mate- 
rials, are  tangent  to  four  of  the  concave  bends  of  the  Left  bank.  If,  how- 
ever, these  bends  are  omitted,  and  averages  of  the  length  and  area  of  ca- 
ving in  the  other  bends  of  the  two  banks  compared,  the  excess  will  still 
be  found  on  the  Right,  or  muddy  water  shore. 

The  assumptions,  therefore,  that  in  the  Mississippi  river,  the  amount  of 
sediment  carried  in  suspension  is  directly  determined  by  the  velocity, 
and  that  the  banks  only  cave  when  the  water  flowing  against  them  has  an 
undercharge  of  sediment  for  its  velocity,  aTe  not  sustained  by  observation 
or  experience. 

The  suspension  of  sediment  is  an  indirect  result  of  velocity,  depending 
more  closely  upon  the  character  of  the  bed — its  symetry,  smoothness  and 
straightness — than  upon  the  velocity,  or  the  relative  depth  of  its  differ- 
ent reaches  and  stages.  Grains  of  sediment  have  no  power  of  movement 
independent  of  the  medium  surrounding  them ; and  friction  alone 
against  a smooth  bed  could  not  impart  the  vertical  movement  to  water 
necessary  to  lift  them.  The  conditions  prevailing  in  large  natural  stream 
beds  are  necessary  for  a great  suspension  of  sediment. 

The  projections,  inequalities  and  sinuosities  of  such  beds  expose  the 
material  composing  them  to  the  impact  or  impingement  of  the  current 
rather  rather  than  to  simple  friction,  and  cause  those  indirect  movements 
of  large  masses  of  water  which,  in  great  rivers,  develop  whirls,  boils  and 
eddies,  and  which  alone  are  capable  of  lifting  numerous  and  coarse  grains 
of  silt,  sand  and  gravel.  When  a boil  rises  in  the  Mississippi  river,  the 
surface  may  be  lifted  many  inches,  and  the  charge  of  sediment  is  so  dense, 
that  it  is  seen  to  roll  away  from  the  crater  in  cloud-shaped  masses.  Mr. 
Clemens  Hershel,  in  his  paper  on  the  “Erosive  and  Abrading  Power  of" 
Water,”  justly  says:  “That  direct  friction  tends  to  drag  materials  along 

the  bed,  or  down  the  banks,  if  they  have  a sufficiently  steep  side-slope,”’ 
and  that  “ The  effect  of  the  simple  friction  of  a stream  upon  its  bed  or 
banks  is  not  a source  of  danger ; its  action  is  very  slow,  and  it  has  never 
been  shown  to  be  of  a dangerous  character  in  any  instance.” 

Besides  these  general  causes  effecting  the  amount  of  sediment  iu  sus- 
pension, it  is  largely  dependent  upon  the  tributary  from  which  then 
main  trunk  is  receiving  most  of  its  discharge.  If  this  is  from  the  Mis- 
souri, the  sediment  is  great  at  any  stage.  If  from  the  Ohio,  the  amount 
may  be  comparatively  small,  even  at  high  stages..  Capt.  M.  R.  Brown? 
U.  S.  Engineer,  a mos£  careful  observer,  in  the  8th  Report  on  the  South 
Pass  Jetties,  p.  32,  states  : “ It  is  also  apparent  that  great  variations  are 
“ found  in  the  ratio  of  sediment  and  of  sand  to  water  through  periods 
“ characterized  by  little  or  no  change  in  the  stages  of  the  river  at  New 
il  Orleans.  The  affluent  which  contributes  most  powerfully  toi  a rise  in 
11  the  river  at  New  Orleans,  undoubtedly  determines,  to  an  important 
“ extent,  the  amount  and  character  of  the  sediment  passing  the  jetties’ 

“ ends,  and  therefore,  the  advance  of  the  20  feet  curve,  and  the  difficulty 
i(  encountered  in  an  effort  to  keep  the  channel  open.” 

This  hypothesis,  claiming  a direct  and  exact  relation  between  the  sedi- 
ment in  suspension  and  the  velocity  of  the  stream,  and  ignoring  the  effect 
of  the  impact  of  the  mass  of  w'ater  in  eroding  the  banks,  is  unsupported 
by  theory  and  experience,  as  well  as  by  the  careful,  scientific  observation 
heretofore  cited.  If  the  predicated  high  water  contraction  had  been 


12 


applied,  giving  uniform  width  and  velocity,  and  in  consequence,  caving 
had  been  checked,  we  should  then  have  less  sediment,  by  the  amount 
now  contributed  by  caving  banks,  and  also  greater  velocity,  because  it 
would  be  relieved  from  the  work  of  suspending  and  transporting  that 
amount  of  sediment.  Under  these  conditions,  why  should  not  erosion, 
if  the  theory  first  prevented  is  true,  be  increased,  rather  than 
diminished  ? 

Again,  uniformity  of  section  affects  only  mean  velocity.  The  extremes 
would  still  vary  greatly,  along  the  bank,  as  it  is  concave  or  convex.  Fill 
and  scour  of  the  bank  would  therefore  continue. 

From  experience,  it  is  known  that,  to  induce  a deposit  up  to  the  level 
of  high  water,  by  contraction  works,  requires  several  years.  Also,  from 
experience  and  the  terms  of  the  theory,  caving  will  not  cease  until 
high  water  contraction  is  complete.  During  this  period  of  bank  develop- 
ment caving  will  therefore  continue  on  the  concave  side,  and  the  line  of 
the  new  convex  shore  and  the  contraction  works  defining  it,  must  be 
annually  advanced  at  an  equal  rate.  If  they  are  not,  by  the  time  com- 
plete results  are  obtained  on  the  original  line,  the  river  will  have  recov- 
ered the  width  that  first  made  contraction  necessary.  If  the  line  is 
annually  advanced  the  cost  of  contraction  will  largely  exceed  that  of 
bank  protection  before  permanent  results  are  secured. 

It  is  essential,  for  the  success  of  this  theory  that  its  application  should 
be  complete.  While  a depth  of  15  feet  at  low  water  will  give  ease  and 
safety  navigation  by  the  present  river  fleet,  the  contraction  works  that 
suffice  to  give  this  depth  have  no  effect  in  arresting  the  caving  in  reaches 
where  they  have  been  constructed.  Were  the  depth  of  thirty  feet,  now 
found  through  the  jetties,  extended  up  the  river,  in  low  water,  to  Cairo, 
it  would  nat  give  the  uniformity  of  section  and  velocity  upon  which  the 
success  of  this  theory  is  predicated.  Should  that  depth  be  obtained, 
-the  fullest  demands  of  commerce  would  be  satisfied,  but  the  work  must 
still  be  prosecuted,  to  the  end  of  arresting  the  caving.  Under  this  aspect 
the  exclusive  use  of  contraction  work  isof  much  greater  proportions,  time 
and  cost,  than  the  direct  application  of  protection  work  to  caving  banks. 

To  conclude — the  protection  of  caving  banks,  while  not  a “ a system” 
or  “ plan'7  in  itself,  is  part  of  any  rational  system  of  river  improvement. 
Neither  jetties,  nor  levees,  uor  revetment,  nor  coptraction  work  consti- 
tutes a system,  of  itself,  any  more  than  does  a dose  of  rhubarb,  or  ginger, 
or  calomel,  or  quinine  constitute  a system  of  medical  practice.  They  are 
all  founded  on  the  same  principle,  and  their  combined  use  is  the  system 
of  improvement  of  alluvial  rivers.  There  is  no  better  jetty,  than  a well 
reveted  bank.  There  is  no  more  practical  contraction  than  holding  a 
bank  that  is  receding  from  your  dike  work  at  the  rate  of  one  hundred 
feet  a month.  Nothing  so  simplifies  and  reduces  the  levee  problem  as  a 
permanent  location;  and,  when  the  bank  resists,  the  bed  must  yield  to 
erosion.  From  these  considerations  follows  the  proper  use  of  bank 
revetment,  as  an  essential  part  of  river  improvement,  in  connection  with 
contraction  by  permeable  spurs  and  dikes,  on  reaches  that  are  undergo- 
ing general  improvement,  as  at  Plum  Point  andLakeProvidei.ee;  also 
where  great  commercial  interest  are  in  jeopardy,  as  in  harbors  and 


13 


^along  city  fronts  ; and  also  to  avert  such  changes  iu  the  river  as  will 
impair  its  navigation,  or  are  at  variance  with  the  theory  and  plans  npon 
which  the  improvement  is  being  conducted,  such  as  cut-offs,  or  the  de- 
flection of  any  large  part  of  its  volume. 

Any  intention  of  a more  extended  or  exclusive  use  of  this  feature  of  the 
work,  such  as  its  application  to  ail  bends,  regardless  of  their  influence  and 
condition,  or  the  abandonment  of  contraction  by  permeable  dikes,  in  the 
many  places  where  such  work  has  an  advantage,  is  absolutely  disclaimed. 

The  plan  for  the  improvement  of  the  Mississippi  River  proposes  to  con- 
trol the  flood  discharge  and  the  direction  of  its  currents  at  all  stages,  to 
secure,  by  its  own  forces,  a capacious  and  unobstructed  bed. 

In  it,  all  the  various  devices  and  constructions  which  will  “ correct,  per- 
manently locate  and  deepen  its  channel,  and  protect  its  banks  ” are  in- 
cluded. No  arbitrary  preference  or  discrimination  in  methods  has  been 
contemplated,  under  the  conviction  that  all  the  resources  of  the  science  of 
Hydraulic  Engineering  will  be  required  for  the  accomplishment  of  the 
great  work. 


It  is  charged  that  the  Mississippi  River  Commission  has  been  derelict, 
in  failing  to  “deflect  the  waters  of  the  Red  River  from  the  Atchafalaya 
into  the  Mississippi.”  Concerning  this  subject,  I desire  to  make  the  fol- 
lowing statement : 

Iu  the  Report  of  Dec.  21,  1883,  p.  15,  it  is  declared  that  “the  Commis- 
sion is  as  mindful  of  the  importance  of  this  part  of  their  work  as  of  its 
difficulties.  Upon  the  completion  of  surverys  and  examinations  now  in 
progress,  full  report  and  recommendations  will  be  made.”  In  the  esti- 
mate accompanying  this  report  an  appropriation  to  repeat  the  work  of 
dredging,  to  maintain  low  water  navigation  through  the  mouth  of  Red 
River  was  recommended  (p.  14).  But  as  a plan  for  permanent  improve- 
ment had  not  been  matured,  no  appropriation  therefor  was  then  advised. 
The  Congress  to  which  this  report  was  submitted  (48th.  1st  sess.)  appro- 
priated for  the  Mississippi,  $3,000,000,  the  amount  estimated  for  specified 
work,  exclusive  of  New  Madrid  and  Memphis  reaches.  But  the  act  of 
appropriation  recited,  among  the  objects  of  expenditure,  the  “Deflection 
of  the  water  of  Red  River  from  the  Atchafalaya  into  the  Mississippi.'  9 
As  no  estimate  had  been  submitted  in  the  report  for  this  special  work,  it 
could  only  have  been  undertaken  by  omitting  some  other  work  recom- 
mended and  for  which  appropriation  had  been  asked  and  made.  Also, 
the  Commission  believed  that  the  deflection  of  the  discharge  of  Red  River 
into  the  Mississippi  involved  danger  of  increased  overflow  on  the  latter 
stream,  of  which  it  was  necessary  to  give  warning,  and  for  which  prepa- 
ration was  necessary  in  the  raising  of  the  levees  below  Red  River.  There- 
fore, it  was  deemed  wise  by  the  Commission,  under  its  advisory  functions, 
to  postpone  action  until  full  discussion  and  recommendations  could  be 
presented  to  Congress.  This  was  done,  at  the  subsequent  session,  in  the 
Report  of  Dec.  19,  1884,  pp.  20-28.  As  that  Congress  (48th,  2nd  sess.) 
passed  no  River  and  Harbor  Bill,  the  Commission  was  unable  to  carry 
out  its  intention  of  immediately  commencing  the  plan  submitted  therein. 


14 


These  recommendations  of  the  Report  of  1884  have  not  been  withdrawn 
or  modified.  On  the  contrary,  they  are  renewed  in  the  report  submitted 
to  the  present  session.  It  is  fair  to  presume  that,  had  appropriations 
been  made  for  the  current  fiscal  year,  the  work  would  now  have  been 
well  advanced ; and  that,  should  the  present  Congress  make  the  necessary 
appropriation,  it  will  be  undertaken  ; as  soon  as  possible. 

B.  M.  HARROD.,  C.  E., 
Member  Miss.  Riv.  Commission. 


****** 


l 


* 


» 


-3 


US?  ;y 

, 0 F'i.iE 

UNIVERSITY  OF  ILLINOIS 


I- 


